Leiomyosarcoma (LMS) is one of the most prevalent soft tissue sarcomas (STS) and can occur in various sites including soft tissue, uterus and retroperitoneal large vessels. Metastatic disease occurs in approximately 50% of patients diagnosed with leiomyosarcoma and prognosis is poor in setting of metastatic disease. A minority of patients benefit from treatment with chemotherapy and early biomarkers of benefit from treatment are lacking. A biomarker of tumor response and patient survival benefit from chemotherapy early in the course of chemotherapy would be of significant impact in treatment planning. Circulating tumor DNA (ctDNA) is present in blood of patients with advanced/metastatic cancer and may serve as biomarker of tumor response to chemotherapy. Blood samples will be collected prior to and during and chemotherapy, and analyzed for ctDNA and for mutations in genes that are associated with increased risk of developing sarcoma. Tumor tissue will be collected and analyzed for changes in genes. Digital images of the sarcoma from CT or MRI scans obtained during treatment will be obtained for advanced radiomic analysis. Study participants will be asked to complete a questionnaire on attitudes and understanding of genetics and genetic testing.